Heretofore, medical treatment of expanding a narrowed blood vessel by a catheter has been performed. For example, in order to expand a stenosis portion of the artery with a balloon catheter in a balloon dilation, a guide wire is inserted into a guiding catheter, so that the distal end is caused to reach the vicinity of the stenosis portion. The balloon catheter is inserted into the guiding catheter in such a manner as to be guided by the guide wire, so that a balloon portion is caused to reach the stenosis portion of the artery. Then, the balloon portion is inflated to expand the stenosis portion of the artery (refer to Patent Literatures 1 to 3).
The balloon dilation has a problem that the frequency of occurrence of restenosis after the operation is high. Although there are various opinions on the mechanism that the restenosis occurs, two phenomena mainly contribute to the occurrence of restenosis. First, the pressurization by the balloon causes mechanical damages (separation, cracking) in a vascular wall to thereby cause chronical migration and hyperproliferation of vascular cells, so that the cavity of the blood vessel is blocked. Secondly, a blood vessel itself is narrowed due to constrictive remodeling of the blood vessel. To address the problem, a technique of simultaneously performing pressurization and heating of a stenosis portion by a balloon catheter, i.e., a heating type balloon dilation, has been devised (refer to Patent Literatures 4 and 5). The heating type balloon dilation is a technique including heating a vascular wall during balloon pressurization to thereby thermally denature (soften) collagen fibers in the vascular wall to perform expansion treatment without causing separation of the vascular wall at a low expansion pressure. The technique can suppress mechanical damages of a blood vessel which is a problem of the balloon dilation.
In the above-described heating type balloon dilation, by heating a heat generating member provided in a balloon, the heat is transmitted to the vascular wall through a fluid (for example, physiological saline, water) for expanding the balloon. However, when the heating amount of the heat generating member is insufficient, the blood vessel is continuously heated over a long period of time in order to increase the temperature of the blood vessel to a target temperature. As a result, a problem that proteins forming the blood vessel are thermally denatured may arise. Moreover, this problem becomes more remarkable with an increase in the capacity of the internal space of the balloon.
Moreover, in the heating type balloon dilation, heat is transmitted to the vascular wall through a fluid (for example, physiological saline, water) for expanding a balloon from a heat generating member heated by irradiation with a light beam, for example. However, when a light source is disposed inside the heat generating member having a cylindrical shape and formed with a metal wire, a light beam emitted from the light source may leak out of a gap generated between the metal wires to the outside of the balloon catheter. This may cause a reduction in the heating efficiency of the heat generating member.